Modern NMR techniques are crucial to understanding intramolecular and intermolecular interactions in proteins and their complexes with other species. The size and complexity of these macromolecules require high field NMR spectrometers (600 MHz or above) to provide sufficient spectral resolution for observation of un-overlapped signals. Researcher sin several departments at Northwestern University are working actively on a series of proteins that would benefit significantly from the use of a state-of-the-art 600 MHz NMR spectrometer. This research includes studies of metalloregulatory proteins, studies of Pb interaction with biomolecules as a means to investigating lead toxicity, studies of heme protein electron transfer processes, investigation of protein-polypeptide interactions in light harvesting complexes, studies of carrier proteins, investigations of enzyme active sites, mechanistic studies of protein folding, and syntheses of sequence specific polypeptides. Many of these studies impact upon interactions in the human body and their effects on disease or metabolic processes. In order to understand better the structures of these macromolecules and the effect on their interactions, sophisticated multidimensional NMR experiments, using modern technology and complex pulse sequences, are needed. Preliminary NMR investigations have been made in several of these research either using an aging and outdated Bruker 600 MHz NMR spectrometer at Northwestern University or by collaborating with researchers at other institutions who have access to the required state of the art instrumentation. The initial results have shown significant promise for more detailed experiments in these areas. Such studies will require much more frequent access to a modern spectrometer allowing extended data acquisitions and access to appropriate pulse sequence experiments. Sufficient instrument time will only be available with the upgrade of the campus 600 MHz NMR spectrometer to current technology as requested in this proposal.